行动代表如何获取调用该方法的实例 [英] Action delegate. How to get the instance that call the method

问题描述

我有一个动作，我想知道如何访问调用该方法的实例。

I have an Action and I wonder how could I access the instance that call the method.

例如：

this.FindInstance(() => this.InstanceOfAClass.Method());
this.FindInstance(() => this.InstanceOfAClass2.Method());
this.FindInstance(() => this.InstanceOfAClass3.Method());



    public void FindInstance(Action action)
    {
        // The action is this.InstanceOfAClass.Method(); and I want to get the "Instance"
        // from "action"
    }

获取Instance
//

谢谢

Thank you

推荐答案

我想你正在寻找 Delegate.Target 属性。

I think you're looking for the Delegate.Target property.

编辑：好的，现在我看看你以后是什么，你需要一个代表动作的表达式树。然后，您可以找到方法调用的目标作为另一个表达式树，构建一个LambdaExpression，编译并执行它，并查看结果：

Okay, now I see what you're after, and you need an expression tree representing the action. Then you can find the target of the method call as another expression tree, build a LambdaExpression from that, compile and execute it, and see the result:

using System;
using System.Linq.Expressions;

class Test
{
    static string someValue;

    static void Main()
    {
        someValue = "target value";

        DisplayCallTarget(() => someValue.Replace("x", "y"));
    }

    static void DisplayCallTarget(Expression<Action> action)
    {
        // TODO: *Lots* of validation
        MethodCallExpression call = (MethodCallExpression) action.Body;

        LambdaExpression targetOnly = Expression.Lambda(call.Object, null);
        Delegate compiled = targetOnly.Compile();
        object result = compiled.DynamicInvoke(null);
        Console.WriteLine(result);
    }
}

请注意，这是非常脆弱的 - 但它应该工作在简单的情况下。

Note that this is incredibly brittle - but it should work in simple cases.

这篇关于行动代表如何获取调用该方法的实例的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！